JP3165363U - Device for positioning optical elements in an optical machine and microscope equipped with the device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for positioning an optical element in an optical machine, in which movement of the optical element is as noiseless as possible and as vibration free as possible, and a microscope equipped with the apparatus.
A gripping mechanism that grips an optical element and is rotatably inserted into a number of predetermined rotational positions, an electric motor that includes an electric motor shaft that rotates the gripping mechanism, and a rotating motion of the electric motor shaft that rotates the gripping mechanism. A transmission mechanism for transmitting to motion, wherein each one of the optical elements is disposed at the target position at the predetermined rotational position, and the transmission mechanism includes a first tooth portion disposed on the gripping mechanism, and This is solved by an apparatus comprising a toothed belt that engages with a second tooth disposed on the motor shaft.
[Selection] Figure 1

Description

  The present invention is an apparatus for positioning an optical element in an optical machine, and includes a gripping mechanism having a number of receptacles for gripping the optical element, an electric motor having an electric motor shaft for rotating the gripping mechanism, and an electric motor And a transmission mechanism for transmitting the rotational motion of the motor shaft to the rotational motion of the gripping mechanism, the gripping mechanism being rotatable to a number of predetermined rotational positions. In the rotational position, each one of the optical elements is associated with the device, which is located at the target position. The present invention also relates to a microscope having such a device.

  An apparatus of the type described above is used, for example, to pivot optical elements such as objectives (objective lenses) or filter blocks held on a rotating disk individually into target positions located in the beam path. Used in the microscope. For that purpose, it is important to bring the optical element to the target position as fast as possible, as noiseless as possible and as accurately as possible.

  Conventional positioning devices typically use a gear motor that drives a rotating disk. For this purpose, a mechanical latch is applied to each optical element, for example formed as a latching notch formed on each optical element, and a spring-biased ball is fastened. If the gear motor is equipped with a freewheel, the disk can move somewhat freely within the region of the target position, so that the ball remains in the latching notch. Such a positioning device is described in Patent Document 1, for example. Further references relating to the prior art are Patent Document 2, Patent Document 3, and Patent Document 4.

  The positioning device of the type described above is disadvantageous in that a relatively powerful motor must be used. This is due to the fact that in the case of a position change, the electric disk must be rotated out of the latch position where the electric disk is fixed. This requires a much greater force than is necessary to simply rotate the disk between the latch positions. Also, with conventional positioning devices, undesirable noise and mechanical vibrations occur when the spring-biased ball travels across the latching notch at a high speed during the rotational movement of the disk traveling across the individual latch positions. This causes an impact stress of the notch flank when the ball entering each latching notch collides with a notch flank facing away from the moving direction.

  Finally, with respect to conventional positioning devices, it is a disadvantage that a latching notch has to be formed (eg attached) on the rotating disk in high-precision positioning with respect to the receptacle on which the optical element is gripped. Subsequent correction of positioning errors, for example caused by tilted optical elements, is impossible.

EP 1 403 672 B1 DE 1 262 121 A DE 296 04 667 U1 DE 199 24 686 A1

  The object of the present invention is to provide a device for positioning an optical element in an optical machine of the kind described above, in which the movement of the optical element is as noiseless as possible and as vibration free as possible. It is also an object of the present invention to provide a microscope in which the optical element can be positioned with little noise and without vibration.

  The present invention solves these problems by the subject matter of claims 1-10.

  According to the present invention, the transmission mechanism includes a first tooth portion disposed on the gripping mechanism and a toothed belt that engages with the second tooth portion disposed on the motor shaft.

  The use of the toothed belt enables the gripping mechanism to transmit the rotational motion of the motor shaft with low noise and no vibration. No latching of the gripping mechanism is necessary to position the optical element at the target location. Thus, mechanical stresses that occur during rotation of the gripping mechanism within the device of the present invention are minimized and thereby extend the operational life of the device.

  The fact that there is no latching also makes it possible to switch to a different optical element faster than before. Solutions known from the prior art typically use elastic latches or similar components that vibrate when latched. This vibration must stop before imaging, for example in an optical machine. Such vibration is not caused by the device of the present invention using a toothed belt. Image formation can be started immediately after reaching the target position.

  The first tooth portion comprises Z1 teeth, the second tooth portion comprises Z2 teeth, and the ratio Z1 / Z2 is a receptacle provided at a uniform angular distance on the gripping mechanism for the optical element N is a natural number that is not 0. With respect to this embodiment, when the motor shaft converts from one predetermined rotational position to the next predetermined rotational position of the gripping mechanism, i.e. when switching from one optical element to the next optical element, Perform n full rotations. This facilitates the control of the motor, especially when n is 1, ie the ratio Z1 / Z2 is equal to the number of receptacles provided on the gripping mechanism for the optical element.

  The electric motor is a stepper electric motor. Such stepper motors ensure accurate and stepwise positioning of the optical elements. Since the device of the present invention does not provide gripping mechanism latching at the target position, a relatively weak and therefore cost-effective stepper motor is sufficient to bring the gripping mechanism to and hold it in the desired rotational position. is there.

  The stepper motor is mounted such that when one of the optical elements is placed at the target position, the motor shaft is in a full step position. This is advantageous when using a conventional stepper motor that does not work at all stages, for example, only at half stages, only at a quarter stage, etc. With this kind of stepper motor, the maximum gripping force as well as the highest positioning accuracy result in all the stage positions of the motor shaft, in which the two adjacent coils of the stepper motor are maximally energized. Thereby, the optical element is fixed at the target position precisely and with the maximum possible gripping force.

  The control mechanism preferably includes an initialization mechanism that controls the stepper motor at the start of the operation of the apparatus so that the motor shaft rotates and reaches a predetermined initial position. This ensures that the gripping mechanism is in a defined rotational position at the start of operation. Advantageously, the initial position mentioned above is one of the predetermined rotational positions, and one of the optical elements is placed at the target position.

  In order to detect a predetermined initial position, the initialization mechanism preferably comprises one light barrier, for example formed as a branching light barrier, and when the gripping mechanism is in the initial position, for example, an optical path slot Detect appropriate code elements such as

  When mounting optical elements, there is probably a minimum residual error that remains within the test tolerances made at the factory. Depending on the application, this residual error may not be desirable, for example because it causes a very small lateral shift in the illumination beam path or for example a field stop image shift. When this deviation is in the rotation direction of the positioning device, fine correction can be performed by closely positioning the optical element immediately next to the originally planned target position. This correctable deviation can be in the angular range of a few seconds. To this end, in a further advantageous embodiment, the control mechanism controls the electric motor while taking into account correction amounts respectively meaning deviation corrections relating to the respective predetermined rotational positions of the gripping mechanism.

  The device of the present invention is preferably limited to positioning an objective mirror and / or filter block in a microscope, usually held on a rotating disk. However, the present invention is not limited to such applications. Rather, it is used to position any optical element that is gripped on a gripping mechanism in an optical machine and that is strictly low noise, vibration free, and rapidly rotated.

  The present invention will be described below based on embodiments with reference to the drawings.

It is sectional drawing of the microscope provided with the positioning device which concerns on this invention. It is a top view of a positioning device. FIG. 6 is an illustration of various embodiments of a toothed belt.

  FIG. 1 shows a fluorescence microscope 10 in cross-sectional view. The fluorescence microscope 10 has a microscope main body 12 on which a tube 14 having a tube lens 16 is attached. A CCD-camera 18 is connected to the tube 14.

  A stage 20 is mounted on the microscope body 12, and a specimen 22 is placed on the stage 20. The specimen 22 is imaged by an objective mirror (objective lens) 24 and brought to view on the CCD-camera 18. The optical axis O passes through the objective mirror 24.

  A light source 26 for irradiating light is disposed on the microscope main body 12, and the light passes through lenses 28 and 30. A first diaphragm 32 and a second diaphragm 34 forming a field diaphragm are disposed between the two lenses 28 and 30.

  The fluorescence microscope 10 includes a positioning device generally indicated at 40. The positioning device 40 includes a disk 42 that can rotate around a rotation shaft 44. The four filter blocks 46, 48, 50 and 52 are gripped against the disc 42 in the receptacle 43 provided for this purpose, which receptacle 43 is not further illustrated in the drawing. In the cross-sectional view of FIG. 1, only filter blocks 46 and 48 are shown, while in the top view of FIG. 2, all four filter blocks 46-52 are shown.

  Each of the filter blocks 46 to 52 includes an excitation filter 54 or 56, a dichroic beam splitter 58 or 60, and a cutoff filter 62 or 64 (see FIG. 1). Excitation filters 54, 56 only allow the transmission of the optical elements of the light emitted by the light source 26, the wavelength of the light being suitable for exciting the specimen 22 and emitting fluorescent emission. The dichroic beam splitters 58, 60 reflect the excitation light transmitted by the excitation filters 54, 56 to the essential points of the optical axis O, so that the excitation light passes through the objective mirror 24 and falls onto the sample 22. The blocking filters 62 and 64 prevent the excitation light reflected by the specimen 22 and entering the objective mirror 24 from entering the tube 14.

  The filter blocks 46 to 52 are different from each other, and the optical elements 54 to 64 contained therein have different characteristics, particularly filter characteristics. By selectively pivoting the filter blocks 46-52 into the optical axis O as described below, different fluorescence incident light may be realized.

  The positioning device 40 further includes a stepper motor 70 having a rotatable motor shaft 72. A toothed disk 74 is mounted on the motor shaft 72 and the toothed disk 74 rotates with the motor shaft 72. The toothed disk 74 has an outer peripheral tooth portion 76 formed by a large number of teeth 78 along the outer periphery thereof.

  The disk 42 that holds the filter blocks 46 to 52 is also formed as a toothed disk. It also includes a tooth portion 80 formed by a large number of teeth 82 along its outer periphery. The tooth part 80 of the disk 42 referred to below as the first tooth part and the tooth part 76 of the toothed disk 74 referred to below as the second tooth part have the same pitch, That is, the teeth 82 or 78 are equally spaced from each other.

  The first tooth portion 80 and the second tooth portion 76 are engaged with a toothed belt 90 having a tooth portion having the same pitch as the pitch of the first tooth portion 80 and the second tooth portion 76.

  The toothed belt 90 is used to transmit the rotational movement of the motor shaft 72 and thus from the toothed disk 74 to the disk 42. Accordingly, the reduction ratio (gear ratio) at which the rotational movement of the motor shaft 72 is transmitted to the disk 42 is the number 78 of teeth 82 provided on the first tooth portion 80 and the teeth 78 provided on the second tooth portion 76. Determined by the ratio to the number of. In this embodiment, the ratio Z1 / Z2 is 4, and is therefore equal to the number of receptacles 43 provided on the disk 42, and the filter blocks 46 to 52 are gripped in the receptacle 43. Thereby, starting from the rotational position of the disk 42 in which one of the filter blocks 46 to 52 is arranged at the target position, ie on the optical axis O, the disk 42 rotates from a quarter rotation of the motor shaft 72 to full rotation. Is achieved, whereby the adjacent filter block is pivoted to the optical axis O.

  The positioning device 40 further includes a control mechanism 100 connected to the stepper motor 70, and the disk 42 rotates to a desired rotational position where each one of the filter blocks 46-52 is pivoted into the optical axis O. The stepper motor 70 is controlled as described above. The control mechanism 100 is further connected to a branch light barrier 102, which is used to initialize the stepper motor 70 to the starting point of operation of the fluorescence microscope 10, that is, to bring the motor shaft 72 to the initial position. It is done. The initial position is determined in advance so that one of the filter blocks 46 to 52 is located at the target position on the optical axis O. For this reason, although not shown, the branched light barrier 102 interacts with the code element formed on the disk 42 and defined at the initial position. This code element can be, for example, a slot that passes through the disk 42, and as soon as it is placed in the region of the branch light barrier 102, the code element is part of the branch light barrier 102. Located above or below the disc 42 (not shown in detail in FIG. 1), it provides an optical path from the light transmission mechanism to the optical receiver. In the case of an optical path, the branched light barrier 102 outputs a detection signal to the control mechanism 100, whereby the control mechanism 100 detects that the disk 42 has been placed at a predetermined initial position.

  The operating element 104 is disposed on the microscope body 12 and connected to the control mechanism 100. The operator can activate the positioning mechanism 70 via the actuating element 104 and bring one of the filter blocks 46-52 to the target position by rotating the disk 42 as desired. Is possible. It is also possible to input a correction amount applied to each rotational position of the disk 42 by the operating element 104. For example, slight misalignment of the filter blocks 46 to 52 can be subsequently corrected by these correction amounts stored in a memory (not shown) provided in the control mechanism 100. Next, when controlling the stepper motor 70, the control mechanism 100 takes these corrections into account.

  While accuracy is discussed below with reference to FIGS. 2 and 3, the positioning mechanism 70 selectively moves the filter blocks 46-52 to the target position. This accuracy affects the position of the field stop image at the position of the sample 22. Therefore, the field stop 34 is imaged by the dichroic beam splitters 58 to 60 on the specimen 22. Different arrangements of the filter blocks 46 to 52 on the disk 42 result in a displacement of the field stop image at the position of the specimen 22.

The rotation of the disk 42 causes a horizontal movement of the field stop image across the specimen 22. When the disc 42 turns out of the target position by an angle δ, the light beam indirectly enters the objective 24 by the same angle δ. The field stop image previously arranged in the center of the specimen 22 is thereby displaced by a distance d [mm] from the center of the image.
d = f · tan δ
Here, f [mm] is a reference focal length, and is a focal length of the tube lens 16 in the present embodiment.

The requirement for the positioning accuracy of the field stop image at the position of the specimen 22 by providing it is that when the field stop image is switched between different filter blocks 46-52, the field stop image is at most +/− Δy at the position of the specimen 22. This means that it may deviate from the center of the required position by [mm], and the maximum angular deviation δ of the disk 42 is as follows.
δ = arctan (Δy / f)

  The predetermined rotational position of the disk 42 must be moved with this angular deviation.

Assuming further that the disk 42 has a radius r [mm], the angle δ is the distance x [mm] on the outer periphery of the disk 42, that is, at the first tooth portion 80 held by the toothed belt 90. Is equal to The following formula applies to x.
x = r · tan δ

  The deviation between the toothed belt 90 and the toothed disk 74 on the disk 42, that is, the gap that the tooth part 90 shows with respect to the first tooth part and the second tooth parts 80, 76 should be smaller than x.

The following values are just an example,
f = 200 mm,
δy = 0.5 mm,
r = 60 mm,
As a result, the value of x is 0.15 mm.

  FIG. 3 shows an embodiment of a toothed belt 90 with different gaps x. According to FIG. 3, the tooth groove to be formed is referred to as “normal groove”, “SE groove” and “0 groove” from top to bottom. Thus, the SE groove represents backlash (tooth surface play) contracted with respect to the normal groove. In the case of the zero groove, the gap x is zero, that is, the toothed belt 90 is securely engaged with the tooth portion 80 or 76.

  The smaller the gap x, the better the positioning accuracy, but the higher the mechanical wear of the toothed belt 90 made of rubber, for example. The limitation of the gap x described above allows a satisfactory compromise to be made between a sufficient positioning system and a minimum possible wear.

DESCRIPTION OF SYMBOLS 10 Fluorescence microscope 12 Microscope main body 14 Tube 16 Tube lens 18 CCD camera 20 Stage 22 Specimen 24 Objective mirror 26 Light source 28 Lens 30 Lens 32 Diaphragm 34 Diaphragm 40 Positioning device 42 Disk 44 Rotating shaft 43 Receptacle 46 Filter block 48 Filter block 50 Filter block 52 filter block 54 excitation filter 56 excitation filter 58 dichroic beam splitter 60 dichroic beam splitter 62 cutoff filter 64 cutoff filter 70 stepper motor 72 motor shaft 74 toothed disk 76 teeth 78 teeth 80 teeth 82 teeth 90 teeth Belt 100 Control mechanism 102 Branching light barrier 104 Actuating element

Claims (10)

An apparatus (40) for positioning an optical element (46, 48, 50, 52) in an optical machine (10), said apparatus comprising:
A gripping mechanism (42) comprising a number of receptacles (43) so that the optical elements (46, 48, 50, 52) can be fixed;
An electric motor (70) comprising an electric motor shaft (72) for rotating the gripping mechanism (42); and
A transmission mechanism for transmitting the rotational motion of the motor shaft (72) to the rotational motion of the gripping mechanism (42),
The gripping mechanism (42) is rotatable into a number of predetermined rotational positions, wherein each one of the optical elements (46, 48, 50, 52) is located at the target position,
The transmission mechanism includes a toothed belt (1) engaged with a first tooth portion (80) disposed on the gripping mechanism (42) and a second tooth portion (76) disposed on the electric motor shaft (72). 90), comprising:
The first tooth portion (80) includes Z1 teeth (82), and the second tooth portion (76) includes Z2 teeth (78), and the ratio Z1 / Z2 is n times the number of receptacles (43). For the optical elements (46, 48, 50, 52), the teeth are provided with an equal angular distance on the gripping mechanism (42);
n is a non-zero natural number, the motor is a stepper motor (70), and
The stepper motor (70) is characterized in that its motor shaft (72) is mounted so that it is in all stages when one of the optical elements (46, 48, 50.52) is placed in the target position. Do the equipment.   The ratio Z1 / Z2 is equal to the number of receptacles (43) provided on the gripping mechanism (42) for the optical element (46, 48, 50, 52). Device (40).   Characterized by an initialization mechanism (100, 102) that controls the stepper motor (70) so that the motor shaft (72) rotates into a predetermined initial position early in the operation of the device (40). A device (40) according to claim 1 or 2.   The device (40) according to claim 3, characterized in that the initialization mechanism comprises a light barrier (102) for detecting a predetermined initial position.   The gripping mechanism is a first toothed disk (42) having a first tooth portion (80) along its outer periphery and a second tooth portion (76) along its outer periphery. Device (40) according to any one of claims 1 to 4, characterized in that a double-toothed disc (74) is attached to the motor shaft (72).   The control mechanism (100) controls the stepper motor (70) while taking into account correction amounts respectively indicating deviation corrections relating to respective predetermined rotational positions of the gripping mechanism (42). The device (40) according to any one of -5.   Apparatus according to any one of the preceding claims, identified as intended for positioning of an objective in a microscope.   The device (40) according to any one of the preceding claims, identified as intended for positioning a filter block (46, 48, 50, 52) in the microscope (10). The toothed belt (90) exhibits a gap x [mm] with respect to the first tooth portion (80) and the second tooth portion (76), and the following condition (1):
x ≦ rtan δ (1)
Where δ = arctan (Δy / f),
r [mm] represents the radius of the disk (42) forming the gripping mechanism,
Δy [mm] represents the tolerance of the image of the field stop (34) located in the microscope (10) at the position of the object (22) from the desired position, and
The apparatus (40) according to claim 8, wherein f [mm] represents a reference focal length.   The microscope (10) provided with the apparatus as described in any one of Claims 1-9.

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